The Covid-19 community case in Northland is the South African strain, Covid recovery minister Chris Hipkins says.
The South African variant may be more infectious than the original strain of coronavirus.
"The source of the infection is highly likely to be a fellow returnee during the person's stay at the Pullman Hotel," Hipkins said.
"This is good news because it means we know where the source of infection is and we don't have to divert our scientists and health experts from other Covid-related work."
The community case - a 56-year-old woman who lives south of Whangarei - was in managed isolation in Auckland's Pullman Hotel.
Director general of health Ashley Bloomfield said the community case had not flagged respiratory symptoms. The woman reported chills and muscle aches but not a runny nose or a cough.
Travellers who stayed in MIQ at the Pullman Hotel from January 9-24 are being asked to self-isolate "immediately", Hipkins said.
Hipkins said of the 253 returnees that exited the hotel within the new infection window 172 had been contacted by 8am.
The person officials believe passed on the infection to the Northland community case arrived in New Zealand on January 9.
Early information suggests transmission happened between this date and January 13.
CCTV footage from the hotel is being reviewed to look for any interaction between the two people, Hipkins said. Officials not believe another person linked the two.
"The review so far has confirmed what we said yesterday - the Northland case has adhered to infection control guidelines in her room and in the exercise space," he said.
"Again, I want to thank her for her diligence."
Monthly audits are made on prevention measures, he said, however an urgent investigation is underway to look again in case further changes can be made.
"That will also include looking at whether returnee movement should be restricted towards the end of their stay in managed isolation after they have had their final test and before they have been released," Hipkins said.
Work was also underway on new filtration devices in the air conditioning in managed isolation facilities, he said.
Returnees at Pullman Hotel kept in MIQ longer
It was decided this morning the release of people staying at the Pullman Hotel will be delayed, Hipkins said.
Forty-six people are impacted by that decision, he said.
Asked about the delay Bloomfield said there would be testing waits in some places. There were 17 sites up and running in the region which were swabbing people for Covid.
"We want people to be tested."
Bloomfield said there was always an increase in the volume of people waiting for tests when something like this happened.
He recommended people took water with them and something to eat.
National moves irs caucus
The National Party has decided to move its first caucus of the year from Whangarei to Wellington in light of the Covid case.
It is due to take place on Monday and Tuesday next week.
"I can't thank the person enough for her dedicated use of the app. Remember this could be anyone at any time."
Ministry couldn't contact all businesses that community case visited
Bloomfield said yesterday that all businesses where the community cases have visited would be contacted before a full list of locations would be published.
The woman's husband has tested negative, Hipkins said this morning, as had another close contact.
She left on January 13 and, after developing Covid symptoms, was tested on Friday January 22.
Between leaving the Pullman and Covid being confirmed on Saturday, she visited 28 places around Northland and anyone there at the same time has been asked to get a test and to self-isolate until the results are known.
The woman arrived back in New Zealand from Europe on December 30 and spent 14 days at the Pullman. After getting a negative tests on January 2 and 10 before leaving.
The woman has been praised for assiduously using QR codes which has given a detailed record of her movements while possibly infectious.
Six cases in managed isolation today
There are six cases of COVID-19 in managed isolation to report since yesterday.
Twenty previously reported cases have now recovered. The total number of active cases in New Zealand is 64. Our total number of confirmed cases is 1,932.
The total number of tests processed by laboratories to date is 1,489,913.
On Sunday, 2,678 tests were processed. The seven-day rolling average up to yesterday is 3,451 tests processed.